Why Does My Window Air Conditioner Sound Like Running Water? [Solution Included]

Window air conditioners could be a godsend on scorching summer days in your home. However, at times, it can make an alarming water sound. 

If your window AC sounds like running water when activating, it’s most likely due to refrigerant circulation, which is normal. However, if the problem persists, chances are the drip hose is clogged or the evaporator coil is frozen. 

While these are the most common reasons, there are others. I will walk you through all the causes so that you can troubleshoot the issue easily.

1. Normal refrigerant circulation 

When your window air conditioner sounds like water, it doesn’t always mean that there is something wrong with your machine.

If the water sound only appears when your air conditioner starts up, chances are it is caused by the refrigerant, and it is a part of normal operation.

When your window air conditioner is turned on, the refrigerant needs to change from dormant to active. The refrigerant will hit the coils during this process, giving off a running water sound.

However, this sound will disappear when the refrigerant flow is stable.

What to do?

Nothing needs to be addressed in this case.

2. Refrigerant pressure is too high or too low

Some customers have reported that their window AC produces a running water sound and never stops. If this is also the case for you, you should take action. 

The refrigerant constantly turns from gas to liquid and then from liquid to gas. When the liquid form of refrigerant passes through the expansion valve, its pressure and temperature will be reduced significantly.

If the refrigerant level is too high or too low, the pressure difference will be large, which will give off a water sound.

What to do?

Unfortunately, this is not something you can do yourself because special tools are required to test the refrigerant level.

In addition, refrigerants are dangerous for our health and environment, so you are not permitted to recharge your window AC. 

HVAC technicians will detect the leaks and fix them when the refrigerant level is low and release some refrigerant when the level is high.

3. Your home is too humid

Many window air conditioners don’t drip water because the collected water will be used directly to cool the condenser coil by making use of a slinger ring. 

Normally, you don’t hear any noise when the ring gets in contact with the collected water. However, the condensate will increase when the room becomes more humid. When the ring hits the water, it will produce a splashing noise.

What to do?

If extreme weather doesn’t show up often, you can wait until the humidity goes down. 

For those who live in a humid area, you can run your AC with a dehumidifier together. This will reduce the excess water and stop the water sound.

4. Frozen evaporator coil 

When you have a window AC, you need to keep up to date with maintenance. A dirty air filter or evaporator coil can reduce the airflow, making your window AC freeze

When the evaporator coil starts to thaw, the excess water can produce a water sound when hitting the drip pan.

What to do?

The most straightforward way to solve this problem is to clean or replace the filter. If it doesn’t work, you should consider cleaning the coil.

Sometimes, a low refrigerant level will also cause the coil to freeze. As I pointed out above, you need the assistance of an HVAC professional. 

5. Clogged drain pipe 

Some old window AC units come with a drain pipe to drain water. Over time, more and more contaminants will accumulate in the pipe and block the water flow, eventually.

The water will back up when the pipe is clogged, causing the drip pan to overflow.

When your window AC is leaking, you may hear a running water sound.

What to do?

Removing the blockage is easy-peasy! Simply disconnect the hose from the unit and use a wire brush to dislodge the gunk and slime. 

Then you can pour some bleach or vinegar through the hose to kill the bacteria and mold and ward off the future growth of these substances.

6. Defective drip pan

The ac drip pan is made of iron, which can get rusted with time. When holes and cracks appear, water in the pan can pass through and get all over the place. As a result, you may hear a sound like water is running.

What to do?

Even though you can repair it by applying some acrylic, epoxy, and polyurethane sealants, this is just a temporary solution. Your best bet is still to replace it with a new pan and luckily, it is inexpensive.

Sum up 

This post has summarized 6 common causes of a window air conditioner sounding like running water. 

While it could be caused by the normal operation of refrigerant circulation when turning on, in most cases, it is because the cleaning is overdue. If your window AC is old, a defective drip pan could also be the culprit.

Hopefully, this post has helped you to combat the problem and get you back to just enjoying a cooling room.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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